This invention relates to a helical scan type information recording/reproducing apparatus, especially to a magnetic tape recording/reproducing apparatus for recording/reproducing a large amount of information on a magnetic tape.
Some prior art examples of a helical scan type information recording/reproducing apparatus are a consumer-use VTR (video tape recorder) represented by the VHS format, a tape pattern of which is shown in FIG. 1, and another consumer-use VTR, known as an 8 mm-Video, a tape pattern of which is shown in FIG. 2. Examples of such apparatus may be seen from the Taniguichi et al U.S. Pat. No. 4,303,950 and the Furumoto et al U.S. Pat. No. 4,390,906.
In FIG. 1 a video tape 1 is provided with a video track 2 on which a video signal is recorded, a control track 3 on which a control signal is recorded, and an audio track 4 on which an audio signal is recorded. The tracing direction of a rotating head is indicated by the arrow 5 and the running direction of the video tape 1 is indicated by the arrow 6. The portions .theta..sub.1, .theta..sub.2 and .theta..sub.3, respectively, of the video track denote winding angles of the video tape wound around a rotating cylinder. The angles .theta..sub.1 and .theta..sub.3 are nearly equal to 5.degree. and the angle .theta..sub.2 is nearly equal to 180.degree.. The angle .theta..sub.2 corresponds to the duration of recording of the video signal, and the angles .theta..sub.1 and .theta..sub.3 correspond to the duration of the margin for maintaining an excahangeability of the two rotating heads.
In FIG. 2 video may be recorded on the track segment 2, while a track segment 7 is utilized for recording a time-compressed audio signal. The numeral 8 designates a first option track, and the numeral 9 designates a second option track. The time-compressed audio signal is produced by converting an audio signal to a PCM signal and compressing the PCM signal to about one-sixth time scale. The portions .theta..sub.1, .theta..sub.2, .theta..sub.3 and .theta..sub.4, respectively, of the video track denote winding angles of the video tape as it is wound around a rotating cylinder. The angles .theta..sub.1 and .theta..sub.3 are nearly equal to 5.degree.. The angle .theta..sub.2 is nearly equal to 180.degree., and the angle .theta..sub.4 is nearly equal to 30.degree.. The angle .theta..sub.4 responds to the duration of recording of the time-compressed audio signal.
As can be seen from the above explanation of the prior art, there are only one or two kinds of information which can be recorded on one slant track with the prior art apparatus. Accordngly, the utilization range of the video tape with the prior art apparatus is very narrow.